Extended area filter bag

ABSTRACT

A bag-type filter adapted for use with a basket filter assembly. The basket assembly is removably supported within a filter vessel and includes an outer, permeable member and an inner, permeable member having a diameter which is less than the diameter of the outer, permeable member such that the inner, permeable member is received with in the outer, permeable member so as to define an annular space therebetween and an inner flow path. The bag-type filter is supported by the basket assembly over both the inner and outer permeable members bounding the annular space therebetween. The bag-type filter includes a first portion having a first, larger diameter and a second portion having a second, reduced diameter. A transition portion is disposed between the first and second portions of the bag-type filter.

[0001] This application claims the benefit of priority from provisionalpatent application Serial No. 60/104,033, filed Oct. 13, 1998 and Ser.No. 60/136,534, filed May 28, 1999 and is a divisional of U.S. Ser. No.09/417,936, filed Oct. 13, 1999.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates, generally, to filters for removingparticulate matter from fluid and, more specifically, to bag filters ofthe type which are supported by a permeable basket which, in turn, isusually positioned in a housing or vessel through which the fluid to befiltered is passed.

[0004] 2. Background of the Invention

[0005] A conventional filter assembly of the type having a basket whichsupports a bag filter and generally known in the related art is shown at10 in FIG. 1. The conventional assembly 10 includes a vessel 12 havingan inlet 14, an outlet 16 and a substantially cylindrical filter chamber18 defined therebetween. A cover 20 is removably mounted to theotherwise open top 22 of the vessel 12. A permeable, filter basket 24 isreceived in the chamber 18 through the top 22 of the vessel 12 and maybe supported by a peripheral flange 26 extending radially inward fromthe inner side wall of the chamber 18. The basket 24 has a diameterwhich is less than the diameter of the chamber 18 and, together, theydefine an annular flow passage 28 therebetween. A cylindrical bag-likefilter element 30 is supported by the basket 24 in the filter chamber18. The filter element 30 may be manufactured from needled felt, meshesor any other material which provides a mechanical straining effect onthe fluid.

[0006] In operation, dirty fluid shown shaded in FIG. 1 enters thechamber 18 through the inlet 14 of the vessel 12 as indicated by arrowsA and flows into the filter element 30 (as indicate by arrows B) whichis supported by the permeable basket 24. The fluid passes through thebag-type filter element 30, as indicated by the arrows C, and is therebycleaned. Clean fluid exits the chamber through the outlet 16, asindicated by the arrows D. During this filtering process, the basket 24does not fill up with particulate. Rather, the bag-like filter element30 becomes coated with the particulate and other unwanted matter. Thebag filter 30 must be replaced at specific intervals which can varydepending upon the application and the purification of the fluid that isrequired. An increase in the back pressure through the vessel 12 isoften used as an indicator that the filter must be changed.

[0007] Filter assemblies of this type are often employed in industrialenvironments to filter water, oil, water soluble oil, paint as well asconsumable fluids such as soft drinks and liquor. Another example of aconventional filter assembly of this type is shown in U.S. Pat. No.4,701,259 issued to Rosaen on Oct. 20, 1987.

[0008] Ultimately, the useful life of the bag-type filter elements isdetermined by the surface area of the filter. The larger the surfacearea, generally speaking, the longer the useful life of the filter.While relatively inexpensive to replace, bag-type filter systems in thepast have suffered from the disadvantage that, in certain applications,the filter elements must be replaced often - sometimes more than once aproduction shift.

[0009] In recognition of this deficiency, it has been proposed toarrange two filters in series in a given vessel or chamber. However,this proposed solution does not result in twice the useful life of thefilter element. Furthermore, the pressure drop across a vessel havingtwo filters in series is approximately twice that of a system employinga single filter element.

[0010] It has also been proposed to employ a pleated filter element inthis environment. Pleated filter elements provide a much higher filtersurface area when compared with bag-type filter elements. This resultsin a longer useful life of the filter element. However, pleated filterelements of the related art suffer from the disadvantage that they aremany times more expensive than the bag-type filter elements.Accordingly, in many manufacturing environments where reducingoperational costs is paramount, pleated filter elements have not beenadopted.

[0011] Thus, there remains a need in the art for a basket filterassembly which employs an inexpensive bag-type filter element with goodfiltering properties, low pressure drop and having a relatively longuseful life.

SUMMARY OF THE INVENTION

[0012] The present invention overcomes the disadvantages in the relatedart in a bag-type filter adapted for use with a basket filter assembly.The basket assembly is removably supported within a filter vessel. Thebasket assembly includes an outer permeable member and an innerpermeable member having a diameter which is less than the diameter ofthe outer permeable member such that the inner permeable member isreceived within the outer permeable member so as to define an annularspace therebetween and inner flow path. The basket assembly is capableof supporting a bag type filter over both the inner and outer permeablemembers bounding the annular space therebetween. To that end, the bagtype filter includes a first portion having a first, larger diameter anda second portion having a second, reduced diameter. In addition, the bagtype filter has a transition portion disposed between the first andsecond portions. The bag type filter is specifically adapted to bereceived on the basket assembly and be supported by the outer and innerpermeable members in the annular space therebetween.

[0013] Accordingly, the bag-type filter of the present inventionprovides a filter surface area which is much larger than conventionalfilter assemblies known in the related art. Thus, the present inventionmay be used to double the useful life of the bag-type filter without anysubstantial increase in cost or to double the flow rate through thevessel for the same useful life of a conventional filter and, while atthe same time in either case, reducing the pressure drop of the fluidthrough the vessel. Alternatively, the present invention facilitates areduction in size of the vessel while maintaining the same respectiveuseful life of the filter. Smaller vessels reduce the plant spacerequired for these filtering systems. Finally, the bag-type filter ofthe present invention is inexpensive, cost efficient and is easy to usein the field.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Other advantages of the invention will be readily appreciated asthe same becomes better understood by reference to the followingdetailed description when considered in connection with the accompanyingdrawings, wherein:

[0015]FIG. 1 is a cross-sectional side view of a conventional filterassembly known in the related art;

[0016]FIG. 2 is a cross-sectional side view of the filter assembly ofthe present invention;

[0017]FIG. 3 is a cross-sectional side view of the basket assemblysupporting a bag-type filter of the present invention having a portionbroken away to show the carriage;

[0018]FIG. 4 is a side view of the outer permeable member of the basketassembly of the present invention;

[0019]FIG. 4A is a top view of the outer permeable member illustrated inFIG. 4;

[0020]FIG. 5 is a side view of the inner permeable member of the basketassembly of the present invention;

[0021]FIG. 5A is a bottom view of the inner permeable member illustratedin FIG. 5;

[0022]FIG. 6 is a cross-sectional, schematic side view showing theassembly path of the inner permeable member received within the outerpermeable member of the basket assembly of the present invention;

[0023]FIG. 7 is a cross-sectional schematic view of the basket assemblyof the present invention;

[0024]FIG. 8 is a side view of the carriage of the present invention;

[0025]FIG. 8A is a top view of the carriage illustrated in FIG. 8;

[0026]FIG. 9 is a cross-sectional side view of one embodiment of thebag-type filter of the present invention;

[0027]FIG. 9A is a top view of the embodiment of the bag-type filterillustrated in FIG. 9;

[0028]FIG. 10 is a cross-sectional side view illustrating the physicalorientation of one embodiment of the bag-type filter when it is in itsassembled position on the basket assembly;

[0029]FIG. 11 is a cross-sectional schematic view illustrating theassembly path of the first embodiment of the bag-type filter onto thecarriage showing the second portion of the bag-type filter receivedwithin the inner diameter of the carriage;

[0030]FIG. 12 is a schematic cross-sectional side view of the assemblypath of the first embodiment of the bag-type filter onto the carriageshowing the first portion of the bag-type filter folded over the outerdiameter of the carriage;

[0031]FIG. 13 is a cross-sectional side view of another, secondembodiment of the bag-type filter of the present invention;

[0032]FIG. 13A is a top view of the embodiment of the bag-type filterillustrated in FIG. 13;

[0033]FIG. 14 is a cross-sectional side view of the first portion of thesecond embodiment of the bag-type filter of the present invention;

[0034]FIG. 15 is a cross-sectional side view of the second portion ofthe second embodiment of the bag-type filter of the present invention;

[0035]FIG. 16 is an elevated top view of the transition portion of onepreferred embodiment of the bag-type filter of the present invention;

[0036]FIG. 17 is a cross-sectional side-view taken substantially throughsection A-A of FIG. 16;

[0037]FIG. 18 is a cross-sectional schematic view illustrating theassembly path of the second embodiment of the bag-type filter onto thecarriage;

[0038]FIG. 19 is a schematic cross-sectional side view of the assemblypath of the second embodiment of the bag-type filter onto the carriageshowing the first portion of the bag-type filter received over the outerdiameter of the carriage;

[0039]FIG. 20 is a schematic cross-sectional side view showing theassembly path of both embodiments of the bag-type filter supported onthe carriage being slipped over the basket assembly; and

[0040]FIG. 21 is a schematic cross-sectional side view illustrating theassembly of the carriage with the basket assembly supporting thebag-type filter.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0041] The present invention overcomes the deficiencies in the relatedart in a filter basket assembly having an extended surface area which isgenerally indicated at 110 in FIG. 2. The assembly 110 includes avessel, generally indicated at 112, having an inlet 114, an outlet 116and a filter chamber 118 defined therebetween. In the preferredembodiment, the filter chamber 118 is elongated and substantiallycylindrical in shape. However, those having ordinary skill in the artwill appreciate that the filter chamber 118 may be any geometric shapewithout departing from the scope of the invention. A cover 120 isremovably mounted to the otherwise open top 122 of the vessel 112. Abasket assembly, generally indicated at 124, is removably received inthe chamber 118 through the top 122 of the vessel 112 and may besupported by any number of support mechanisms. For example, the basketassembly 124 may be supported by a support extending from the wall ofthe filter chamber 118; by suspending the basket assembly 124 from theupper lip at the top 122 of the vessel 112; or by a support which spacesthe basket assembly 124 from the bottom 123 of the vessel 112. Howeverand in the preferred embodiment, the basket assembly 124 is supported bya peripheral flange 126 extending radially inward from the inner sidewall of the chamber 118 near the inlet 114. The basket assembly 124 hasa diameter which is less than the diameter of the chamber 118 andtogether they define an outer annular flow passage 128. While the vessel112 illustrated in the figures supports a single basket assembly 124,those having ordinary skill in the art will appreciate that the presentinvention is not limited to single basket vessels and may be employedwith vessels supporting multiple basket assemblies and filters.

[0042] The basket assembly 124 will be described in greater detail withreference to FIGS. 3-7 of the drawings. Referring specifically to FIGS.3, 4, 4A, 5 and 5A, the basket assembly 124 includes an outersubstantially cylindrical, permeable member 130 and an innersubstantially cylindrical, permeable member 132. However, those havingordinary skill in the art will appreciate that the inner and outerpermeable members 130, 132 may take any geometric shape withoutdeparting from the scope of this invention. The outer permeable member130 defines a pair of opposed, open ends 131, 133. The inner member 132has one permeable arcuate end 134 and a flange 135 located at theopposite open end of the inner permeable member 132. The inner member132 has a diameter which is less than the diameter of the outer member130 and is received in the outer member 130 such that the flange 135 maybe connected to the open end 133 as by welding with a continuous weldbead or any other suitable means as shown in FIGS. 6-7. The other openend 131 of the outer permeable member 130 is adapted to be received andsupported by the peripheral flange 126 extending radially inward fromthe inner side wall of the chamber 118. Together, the inner and outerpermeable members 132, 130, respectively, define an annular space 136therebetween and an inner flow path 138 interior of the annular space136. The inner and outer permeable members 132, 130 may be made of apermeable metal or plastic including stainless steel, wire mesh or anyother suitable structure which allows fluid to pass therethrough butwhich is structurally capable of supporting a filter bag as will bedescribed in greater detail below. In the preferred embodiment, theinner and outer permeable members 130, 132 are made of a 304 gradepassivated stainless steel.

[0043] The assembly 124 may also employ a carriage, generally indicatedat 140 in FIGS. 8 and 8A. In the preferred embodiment, the carriage 140is elongated and substantially cylindrical in shape. However, thosehaving ordinary skill in the art will appreciate that the carriage 140may be any geometric shape without departing from the scope of theinvention. Furthermore the carriage may take any shape which effectivelyaccommodates the bag-type filter as described in greater detail below.The carriage 140 has a pair of opposed open ends 141, 143 with aplurality of annularly spaced rods 145 extending therebetween. In thepreferred embodiment, the rods 145 are ¼ inch in diameter and are madeof 304 grade stainless steel. Because of the structure of its preferredembodiment and its appearance as illustrated in FIG. 8, the carriage 140is often referred to as a “wire” carriage.

[0044] The wire carriage 140 is a tool used to insert the extendedbag-type filter into the basket assembly 124. One embodiment of theextended bag-type filter of the present invention is generally indicatedat 142 in FIGS. 9-10 and another embodiment is generally indicated at242 in FIGS. 13-14. In the first preferred embodiment, the filter 142 issubstantially cylindrical in shape and has a first portion 144 having afirst, larger diameter, a second portion 146 having a second, reduceddiameter and a transition portion 148 disposed therebetween. Thetransition portion 148 may be formed merely by a reduction in thediameter of the extended area filter. Alternatively, the transitionportion 148 may take the form of a circular piece of filter materialwhich defines an inner diameter 152 and an outer diameter 154. Thetransition portion 148 is attached to the first portion 144 of thefilter 142 at the outer diameter 154 of the transition portion 148.Similarly, the transition portion 148 is also attached to the secondportion 146 of the filter 142 at the inner diameter 152 of thetransition portion 148. The filter 142 also has an arcuate closed end150 and an open end 151 defined by an annular ring which is locatedopposite the closed end 150 when the filter 142 is in and extendedposition as illustrated in FIG. 9. On the other hand, the arcuate closedend 150 is positioned adjacent the open end 151 when the filter is inits assembled position as illustrated in FIG. 10. The filter element 142may be disposable, non-reusable and may be manufactured from needledfelt, meshes or any other material which provides a mechanical strainingeffect on the fluid. In the preferred embodiment, the filter 142 is madeof a micron rated fabric which may provide, for example, six to sevensquare feet of filtration surface area in the approximate proportionalsize depicted in these Figures. However, those having ordinary skill inthe art will appreciate that the area of the filtration surface of anygiven filter 142 will vary with the size of the vessel 112 and basketassembly 124.

[0045] As shown in FIGS. 11-12 in connection with the first embodimentof the filter 142, the second portion 146 is received within the innerdiameter defined by the cylindrical wire carriage 140. The first portion144 of the bag-type filter 142 is then folded over the outer diameter ofthe wire carriage 140. The transition portion 148 facilitates this stepand bridges one annular open end 141 of the wire carriage 140 betweenits inner and outer diameter.

[0046] On the other hand, the wire carriage 140 may also be used inconjunction with an alternative, second embodiment of the extended,bag-type filter generally indicated at 242 in FIGS. 13 and 13A. Thealternate embodiment of the filter 242 enjoys the advantage that it iseasy to manufacture. Like that of the first embodiment, in the secondpreferred embodiment, the filter 242 is substantially cylindrical inshape and has an outer, first portion 244, shown in FIG. 14, having afirst, larger diameter; a second portion 246, shown in FIG. 15, having asecond, reduced diameter; and a transition portion 248, generally shownin FIGS. 16-17, disposed therebetween. The first portion 244 includes apair of opposed, open ends 245, 247. The second portion 246 includes oneopen end 249 and an arcuate, closed end 250. The open end 245 of thefirst portion 244 is defined by an annular ring which is positionedabout the arcuate, closed end 250 when the filter 242 is in itsassembled position as illustrated in FIG. 13.

[0047] Referring specifically to FIGS. 16-17, the transition portion 248is substantially U-shaped in cross-section having an annular, innerflange 252; an annular, outer flange 254; and an arcuate, bridge portion256 formed therebetween. On end 247 of the first portion 244 is attachedto the outer flange 254. Similarly, one end 249 of the second portion246 is attached to the inner flange 252 by any manner, including, butnot limited to, gluing, heat setting, sewing, crimping, or anymechanical or chemical method known in the art or yet to be discovered.The transition portion 248 has a relatively high stiffness or rigidityrelative to the filter 242 and is preferably one piece and made frommolded polyethylene. However, the transition portion 248 may be formedin a number of ways including, for example, by two L-shaped membersbonded together.

[0048] Those having ordinary skill in the art will recognize that thetransition portion 248 may be formed in many ways. For example, thefirst portion 244 and the second portion 246 may be attached in a numberof ways such as by sewing, glueing, laser welding or otherwise heatsealed, or crimped together. In any event, the filter element 242 isdisposable and non-reusable and may be manufactured from needled felt,meshes, or any other material which provides a mechanical strainingeffect on the fluid. In the preferred embodiment, the filter 242 is madeof a micron rated fabric which may provide, for example six to sevensquare feet of filtration surface area in the approximate proportionalsize depicted in these figures. However, those having ordinary skill inthe art will appreciate that the area of the filtration surface of anygiven filter 242 will vary with the size of the vessel 112 and of thebasket assembly 124.

[0049] As shown in FIGS. 18-19, the second portion 246 is receivedwithin the inner diameter defined by the cylindrical wire carriage 140.The first portion 244 of the bag-type filter 242 is received over theouter diameter of the wire carriage 140. The transition portion 248bridges one annular open end 141 of the wire carriage 140 between itsinner and outer diameter.

[0050] As shown in FIGS. 20-21, the wire carriage 140 supporting thefilter 142,242 of either embodiment is then flipped 180° such that itmay be received within the annular space 136 formed between the inner132 and outer 130 members of the basket assembly 124 and such that theclosed end 150,250 of the filter is cooperatively engaged by thepermeable arcuate end 134 of the inner member 132. The basket assembly124 is then inserted into the chamber 118 of the vessel 112 as shown inFIG. 2. The wire carriage 140 may then be removed. Alternatively, thewire carriage 140 may be used solely to insert the filter 142, 242 intothe basket assembly 124. However, those having ordinary skill in the artwill appreciate that the wire carriage is not essential and that thefilter 142,242 could be properly fitted about the basket assembly 124without it.

[0051] As best shown in FIG. 2, dirty fluid shown shaded in FIG. 2enters the vessel 112 through the inlet 114 as indicated by the arrowsA. The dirty fluid then enters the annular space 136 between the innerand outer permeable members 132, 130 of the basket assembly 124 asindicated by the arrows B. In most operational environments, the dirtyfluid will fill the annular space 136 until it is at or above thepermeable, arcuate end 134 of the inner member 132. The dirty fluid thenpasses through the basket assembly 124 through the filters 142, 242 andinto either the outer, annular flow passage 128 or the inner flow path138 as indicated by the arrows C. Clean fluid then exits the filterchamber 118 through the outlet 116, as indicated by the arrows D.

[0052] The dirty fluid passes through the filter 142,242 just once, butthe effective surface area of the filter 142,242 has been doubledthrough the use of a bag-type filter 142,242 having first portions144,244 and second portions 146,246 supported by the wire carriage 140about both the inner and outer baskets 132, 130. Because of its extendedfilter surface area, the present invention may be employed to at leastdouble the useful life of the bag-type filter without any substantialincrease in costs while, at the same decreasing the pressure drop (ΔP)of the fluid through the vessel. More specifically, beta site testing ofthe filter assembly of the present invention has revealed that anextended area bag type filter of the present invention havingapproximately double the surface area over a comparable conventionalfilter subjected to the same flow rate results in three to four timesthe useful filter life over a conventional filter. This is because theimpact velocity of the solid particles in the dirty fluid against theextended area filter is reduced by approximately ½ when compared toconventional filter assemblies. In addition, use of the extended areafilter assembly of the present invention reduces the initial pressuredrop (ΔP) by approximately ½ when compared to the initial pressure dropacross conventional filter assemblies. Alternatively, the size of thevessel may be reduced by employing the filter assembly of the presentinvention while maintaining the same respective useful life of thefilter. Smaller vessels reduce the plant space required for thesefiltering systems. Finally, the extended area bag-type filter of thepresent invention is inexpensive, cost-efficient and is easy to use inthe field.

[0053] The invention has been described in an illustrative manner. It isto be understood that the terminology which has been used is intended tobe in the nature of words of description rather than of limitation. Manymodifications and variations of the invention are possible in light ofthe above teachings. Therefore, the invention may be practiced otherthan as specifically described.

I claim:
 1. A bag-type filter adapted for use in connection with abasket filter assembly, said bag type filter comprising: a first portionhaving a first, larger diameter, a second portion having a second,reduced diameter and a transition portion disposed therebetween; saidbag type filter being adapted to be received on a basket assembly.
 2. Abag-type filter assembly as set forth in claim 1 wherein said second,reduced diameter portion of said bag-type filter includes an arcuate,closed end, said first, larger diameter portion having an open end, saidarcuate, closed end of said second, reduced diameter portion beingpositioned adjacent said open end of said first, larger diameter portionwhen the bag-type filter is supported by said basket assembly.
 3. Abag-type filter as set forth in claim 1 wherein said transition portionincludes a circular piece of material having an inner diameter and anouter diameter; said transition portion being attached to said firstportion of said filter at said outer diameter of said transition portionand attached to said second portion of said filter at said innerdiameter of said transition portion thereby forming a bridgetherebetween.
 4. A bag-type filter as set forth in claim 1 wherein saidtransition portion is defined by a reduced diameter segment of saidbag-type filter.
 5. A bag-type filter as set forth in claim 1 whereinsaid first, larger diameter portion has at least one open end, saidsecond, reduced diameter portion includes an arcuate, closed end and atleast one open end, said transition portion is substantially U-shaped incross-section having an inner flange, an outer flange, and a bridgeportion defined therebetween, and wherein said open end of said first,larger diameter portion is attached to said outer flange of saidtransition portion and said open end of said second, reduced diameterportion is attached to said inner flange of said transition portion. 6.A bag-type filter as set forth in claim 5 wherein said transitionportion is an integral, one-piece, member being substantially U-shapedin cross-section.
 7. A bag-type filter as set forth in claim 1 whereinsaid transition portion is defined by two L-shaped members attached toone another so as to be substantially U-shaped in cross-section.